Changes in law tucked into the 2009-'11 state budget recently opened up the door to such contracts between school boards and their professional staff -- namely teachers -- while also lifting controls on teacher salaries.

The memo to school boards from WASB staff counsels Bob Butler and Barry Forbes, however, cautions districts about how they approach changes in the law.

For one, the attorneys warn against approving four-year contracts, on the grounds that they might lock school systems into expenditures without knowing their revenue limits, set every two years by the Legislature.

And then there's the problem with something called "whipsawing," which the lawyers call "a union tactic in which the latter years of multi-year settlements are inordinately high, but the long-term average within each district seems more reasonable."